B

Rivers are one of our most important natural resources(资源). Since the Dam beginning of history, people have used rivers for transportation. Rivers

also give food to eat, water to drink, water for crops, and chances far-fun. In

order to increase the supply( 供给)of water for crops, engineers sometimes

build a dam across a river. Then people can use the water not only to provide

water for their fields but also to make electricity for their homes and

industries.

Rainforests are Earth's oldest living ecosystems( 生态系统),and some are in their present form for at least 70 million years. They are unbelievably rich, home to more than half of the world's plant and animal species(物种)-even though they cover just 6% of Earth Rainforests' rich kinds are very important to our humans and our planet. They help change our climate and

provide us with everyday products.

Roads are everywhere and sometimes seem like part of the natural views. But in fact, road building can have bad influence on both plant life and animal life. One bad environmental influence of roads is that they cause the movement of plant species from one area to another.

When a new plant species gets into an area where it wasn't growing before, the new plants compete for resources with the present plant life.

(▲)71.What do the three passages mainly talk about?

A.The environment pollution and protection.

B.The importance of natural resources and ecosystems.

C.The Destruction( 破坏 )of ecosystems and natural resources.

(▲)72.How many uses of the rivers are mentioned in the first passage?

A.5

B.6

C.7

(▲)73.In the last passage, what will the writer most probably write next?

A.How do people build the roads?

B.How do the present plants move to other places?

C. How does road building influence the animal life?

(▲)74. Which of the following is TRUE according to the passages?

A.Dam can be used for making electricity.

B. Road building is good for the ecosystems.

C.Rainforests are changing their forms all the time.

(▲)75. What can we learn from the passages?

A.We can do road and darn building as much as possible.

B.Rivers and rainforests are independent from the ecosystem.